Conventional footwear has structural limitations that force the wearer to make difficult choices between style and comfort. As a result, many individuals endure significant foot pain, or elect to wear less attractive shoes or styles that may not be appropriate for the occasion. To address this problem, some women carry additional footwear in a car or large bag. However, a spare pair of conventional shoes is less than ideal because of size and bulk limitations on portability. Lightweight rollable or foldable shoes are available that offer increased portability. However, such products do not contain the support, durability, comfort or style desired in a non-foldable shoe.
Moreover, prior art foldable shoes have outsoles that do not adequately protect the shoe midsole and upper, leading to premature wear of the shoe including tearing and damage to the shoe. Furthermore, such shoes are typically flimsy or, in other words, do not provide adequate support or protection of the foot. For instance, many foldable shoes have an overall spring constant that is, depending on the brand and model, between 0.14 kilogram-force/inch and 0.34 kilogram-force/inch. Such shoes provide little or no resistance, protection and support, and thus are inadequate to wear for repeated or extended use, particularly outside or on rough terrain (e.g., dirty pavement, stones, etc.). Moreover, such shoes are not durable enough to last a normal shoe lifespan even with only moderate use. Therefore, while some footwear designs have attempted to bridge the gap between full time and portable shoes, there remains no practical solution.
In prior art shoe manufacturing processes, outsoles are sewn onto a midsole. These outsoles are at the bottom of the shoe and protect the midsole and upper from wear and tear and further provide support and rigidity to the entire shoe. After the outsoles have been sewn on, the midsole is sewn to the upper and an insole thereby forming a single seam. This single seam traverses the perimeter of the shoe and essentially delineates the shoe upper from the midsole. While such processes are advantageous because of manufacturing efficiencies, the drawback with such approaches is realized when one considers the properties of the outsoles. The sewing wheel of the sewing machine used to sew the midsole, the upper, and the insole together interferes with the outsoles previously sewn onto the midsole. As a result, a dilemma arises. The ideal outsole patches serve to 1) protect the foot, 2) provide comfort, and 3) provide durability by protecting the seam attaching the midsole, outsole and insole. Thus, the ideal outsole patches are thick and wide such that the perimeter of the outsoles is close to the seam. Yet, as the outsole becomes thicker and is brought closer to the seam that attaches the upper, midsole and insole, the seam becomes more difficult and eventually impossible to stitch. Thus, prior art shoes are constructed with either (i) thin and wide or (ii) narrow and thick outsole patches. Moreover, prior art shoes are limited on their ability to add cushion inserts below the insole because such cushion inserts make the seam even less manageable and force more narrowing and thinning of the outsole patches leading to greater instability and/or lower durability of the shoe and protection of the foot. Thus, in prior art shoes, shoe comfort and durability is traded off for shoe stability. Thus the dilemma become apparent. If the outsole is made thick and narrow, the lack of support due to the gap between the perimeter of the outsoles and the seam becomes noticeable and uncomfortable and the seam, upper and midsole are left exposed to the ground. If the outsole is made thin and wide, the lack of support due to the gap between the perimeter of the outsole and the seam is not as noticeable. However, in such instances, the upper, midsole and seam are exposed to the ground, the outsole wears more quickly and the shoe provides limited protection and comfort.
Given the above background, what is needed in the art are improved foldable shoe designs and improved shoe manufacturing processes.